Nitrobenzene precautions

Health nd Safety Factors. The mononitrochlorobenzenes are toxic substances which may be absorbed through the skin and lungs giving rise to methemoglobin. Their toxicity is about the same as or greater than that of nitrobenzene. The para isomer is less toxic than the ortho isomer, and the maximum allowable concentration that has been adopted for -nitrochlorobenzene is 1 mg/m (0.1 ppm) (6). The mononitrochlorobenzenes are moderate fire hazards when exposed to heat or flame. They ate classified by the ICC as Class-B poisons. The same handling precautions should be used for these compounds as are used for nitrobenzene. 

The feed consists of 3 to 7% HNO3, 59 to 67%H2S04, and 28 to 37% water. Sulfuric acid is necessary to adsorb the water and energy generated by the heat of reaction. The plant, which produces 15,000 lb nitrobenzeneUi, requires one or two operators per shift together with a plant supervisor and part-time foreman. This exothermic reaction is carried out essentially adiabatically, so that the temperature of the feed stream rises from 90°C to 135°C at the exit. One observes that the nitrobenzene stream from the separator is used to heat the benzene feed. However, care must be taken so that the temperature never exceeds 190°C, where secondary reactions could result in an explosion. One of the safety precautions is the installation of rehef valves that will rupture before the temperature approaches 190°C, thereby allowing a boil-off of water and benzene, which would drop the reactor temperature. 

Precaution Probably combustible incompat. with nitrobenzene, potassium hydroxide, strong oxidizing agents Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of CO, CO2 Storage Store under ambient temps. keep away from oxidizing materials Uses Dyes... 

Properties Wh. flakes, lumps or pellets sol. in water, alcohol, glycerol si. sol. in ether m.w. 56.11 dens. 2.044 m.p. 405 C b.p. 1320 C Toxicology ACGIH TLV/CL 2 mg/m LD50 (oral, rat) 365 mg/kg toxic by ing., inh. strong caustic eye and severe human skin irritant ing. may cause violent throat pain and stricture of esophagus mutagenic data TSCA listed Precaution DOT Corrosive material releases heat in contact with water and acids corrodes many metals when wet violent exothermic reactions with water potentially explosive reactions with chlorine dioxide, nitrobenzene, nitromethane... 

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